Hijackers usually have a motive, and historically the motives typically involved some form of monetary exchange or demands for political asylum. You don't generally hijack a plane unless you either want to go somewhere or you want something in return.

That doesn't mean it's impossible for a hijacking to be done quietly, with no demands, but it's further complicated by the fact that the aircraft has to land somewhere. It's also somewhat difficult to hide a plane as large as a 777, much less find an airport to land it where it'll go unnoticed. This increases the likelihood that if it were a hijacking, it was probably similar to PSA flight 1771 [1] and more inline with a murder/suicide than a ransom.

Although, imagine the possibilities terrorists could use a 777 for. Load it with explosives, biological weapons, radioactive materials... It's enough to make a politician want to ban flying altogether. Let's hope they don't find my comment.

Regardless, I'm not especially comfortable wagering a bet on the cause of MA370's disappearance. My initial instinct was to presume foulplay or an in-flight fire. Now I'm not so sure.

If the aircraft isn't found, I suspect this might become the mystery of the century.

[1] http://en.wikipedia.org/wiki/PSA_Flight_1771